用openlayer显示google地图

花了一天的时间，从google.ditu下载了地图数据，让后用在openlayer做前台进行显示，完美完成。除了数据不合法一切都好用，有空可以研究一下怎么生成数据。

<script type="text/javascript">
if (location.search == "") {
   lon=120.363808;
   lat=36.088506;
   zoom=17;}
   //http://ditu.google.cn/?ie=UTF8&ll=31.230344,121.472569&spn=0.015633,0.026436&z=15
   //http://ditu.google.cn/maps?f=q&hl=zh-CN&geocode=&q=%E9%9D%92%E5%B2%9B&ie=UTF8&ll=36.088506,120.363808&spn=0.118745,0.211487&z=12&iwloc=addr
var PI = 3.14159265358979323846;
lon = lon * 20037508.34 / 180;
lat = Math.log (Math.tan ((90 + lat) * PI / 360)) / (PI / 180);
lat = lat * 20037508.34 / 180;
</script>
<script type="text/javascript" src="OpenLayers.js">
</script>

var map;
function get_imap_url (bounds) {
        var res = this.map.getResolution();
        var x = Math.round ((bounds.left - this.maxExtent.left) / (res * this.tileSize.w));
        var y = Math.round ((this.maxExtent.top - bounds.top) / (res * this.tileSize.h));
        var z = 17 - this.map.getZoom();
       
        //----------------------------------
        //shanghai 109760 53556 qingdao 109344 51424 from coords.txt
        //naming rule://map/1x/000/1x000000.png
        var myBounds={left:109344,top:51424};//109344 51424
        var myDir0=Math.pow(2,z);       

        x = Math.round (x - myBounds.left/myDir0 );
        var myTileNum="000";
        if(x>=0){
           myTileNum=x.toString();
           if(myTileNum.length==1)myTileNum="00"+myTileNum;
           if(myTileNum.length==2)myTileNum="0"+myTileNum;
           }
        y =Math.round (y - myBounds.top/myDir0 );
        var myTileDir="000";
                if(y>=0){
           myTileDir=y.toString();
           if(myTileDir.length==1)myTileDir="00"+myTileDir;
           if(myTileDir.length==2)myTileDir="0"+myTileDir;
           }  
       
        var path = myDir0+"x/"
        + myTileDir + "/"
        + myDir0+"x" + myTileDir + myTileNum + "." + this.type;
        if(x<0 || y<0)path="blank.gif";
        var url = this.url;
        if (url instanceof Array) {
            url = this.selectUrl(path, url);
        }       
        //alert(url + path);
        return url + path;
    }

function init()
{
   map = new OpenLayers.Map ("map", {
    controls:[
     new OpenLayers.Control.Permalink(),
     new OpenLayers.Control.MouseDefaults(),
     new OpenLayers.Control.LayerSwitcher(),
     new OpenLayers.Control.MousePosition(),
     new OpenLayers.Control.PanZoomBar()],
    maxExtent: new OpenLayers.Bounds(-20037508.34,-20037508.34,20037508.34,20037508.34),
    numZoomLevels:19, maxResolution:156543, units:'meters', projection: "EPSG:41001"} );

googleAtHome = new OpenLayers.Layer.TMS(
   "google@home",
   "http://dev.openstreetmap.org/~ojw/Tiles/cycle.php/",
   {type:'png', getURL: get_goo_url} );

myHome = new OpenLayers.Layer.TMS(
   "My@home",
   "http://localhost:8080/map/",
   {type:'png', getURL: get_imap_url} );

        //map.addLayers([layerThis, layerMultihost, layerTilesAtHome, layerFirefishy, layerSebastian, layerMaplint, layerCycleAtHome, layerMapnik, googleAtHome,myHome]);
        map.addLayers([googleAtHome,myHome]);

   map.setCenter (new OpenLayers.LonLat(lon, lat), zoom);
}